Combustion over water Help!!!!

njw · November 12, 2011, 14:20

Hi there,

I am relatively new to Ansys and CFD in general and am having big problems with setting up a transient methane-oxygen combustion system over a free surface of liquid water on CFX.

I am trying to model both the liquid and gas phases and couple the two to determine evaporation rates and convection cells in both phases.
To start off I only have a simple 2D channel with free-slip walls everywhere except an opening at the end. I know its inaccurate but for the sake of computation time I am using the eddy dissipation and k-e models for combustion and turbulence respectively.

The system works without any ignition source present; the combustible atmosphere exists above the liquid surface. However, when I try to introduce a point energy source to ignite the mixture, the solver crashes on the first iteration loop every time.

Advice would be greatly appreciated!
Thanks

ghorrocks · November 13, 2011, 17:58

Does the free surface move? Have waves? Splashes, foam, bubble entrapment or anything like that?

November 12, 2011, 14:20	Combustion over water Help!!!!	#1
njw New Member Neal Wannell Join Date: Nov 2011 Posts: 5 Rep Power: 15	Hi there, I am relatively new to Ansys and CFD in general and am having big problems with setting up a transient methane-oxygen combustion system over a free surface of liquid water on CFX. I am trying to model both the liquid and gas phases and couple the two to determine evaporation rates and convection cells in both phases. To start off I only have a simple 2D channel with free-slip walls everywhere except an opening at the end. I know its inaccurate but for the sake of computation time I am using the eddy dissipation and k-e models for combustion and turbulence respectively. The system works without any ignition source present; the combustible atmosphere exists above the liquid surface. However, when I try to introduce a point energy source to ignite the mixture, the solver crashes on the first iteration loop every time. Advice would be greatly appreciated! Thanks

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November 13, 2011, 17:58		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Does the free surface move? Have waves? Splashes, foam, bubble entrapment or anything like that?